δεινός from δέος, properly δεεινός, cf. ἐλεεινός, ἐλεινός, from ἔλεος fearful, terrible, dread, dire, Hom., etc.; δεινὸν ἀϋτεῖν, βροντᾶν to shout, thunder terribly, Il.; δεινὸν δέρκεσθαι, παπταίνειν, ἰδεῖν to look terrible, Hom.; but, δεινὸς ἰδέσθαι fearful to behold, Od.; δεινὸς μὲν ὁρᾶν, δεινὸς δὲ κλύειν Soph.:— τὸ δεινόν danger, suffering, awe, terror, Hdt., Aesch., etc.; so, τὰ δεινά Soph., etc.:— οὐδὲν δεινοί, μὴ ἀποστέωσιν no fear of their revolting, Hdt.:— δεινὸν ποιεῖσθαι to take ill, complain of, be indignant at a thing, Lat. aegre ferre, Hdt., etc.; δεινὰ παθεῖν to suffer dreadful, illegal, arbitrary treatment, Attic; so in adv., δεινῶς φέρειν Hdt.; δ. ἔχειν to be in straits, Xen. with a notion of Force or Power, mighty, powerful, δεινὸν σάκος the mighty shield, Il. simply, wondrous, marvellous, strange, τὸ συγγενές τοι δεινόν kin has a strange power, Aesch.; δ. ἵμερος, ἔρως, δέος Hdt.; δεινὸν ἂν εἴη, εἰ . . , it were strange that . . , Eur.:—adv. -νῶς, marvellously, exceedingly, δ. μέλας, ἄνυδρος Hdt. the sense of powerful, wondrous passed into that of able, clever, skilful, Hdt., Attic; esp. of practical ability, opp. to σοφός, Plat.: c. inf., δεινὸς εὑρεῖν clever at inventing, Aesch.; δεινὸς λέγειν Soph.; δεινὸς πράγμασι χρῆσθαι Dem.: also c. acc., δεινὸς τὴν τέχνην Plat.; δ. περί τι or τινος Plat.